Pile loom

ABSTRACT

There is provided an apparatus capable of maintaining a pile warp tension at a desired value even under a high speed operation of a pile loom in a pile warp tension controller of the pile loom. The pile warp tension controller controls a biasing force relative to a tension roller in synchronization with a relative motion between a reed and a woven cloth which is performed in correspondence with a pile formation, and also controls the biasing force relative to the a tension roller so as to apply a tension in a prescribed period including at least a beating time for pile formation within a period where the relative motion is performed, which tension is lower than an applied tension in a period other than the period where the relative motion is performed, and the tension roller is elastically deformable in the range of a winding of the pile warp.

FIELD OF THE INVENTION

[0001] The invention relates to a pile loom for driving a tension rollerrelative to a pile warp associated with pile weaving and for setting apile warp tension at an appropriate value.

BACKGROUND OF THE INVENTION

[0002] Japanese Patent Publication No. 50-39177 (Sulzer) discloses atechnique for passively driving a tension roller in a pile loom.According to the technique of Sulzer, the tension roller is supported tobe freely swung while the tension roller is biased by a spring and thelike, and a warp is wound around the tension roller and the tensionroller is curved and deformed by a warp tension.

[0003] According to the technique of Sulzer, although the tension rolleris structured to be displaceable while undergoing a variation of tension(hereinafter referred to as tension variation), the tension roller cannot substantially follow a sharp tension variation such as a sheddingmotion but operates while delayed from the time of tension variation.During the weaving operation, the tension roller has to absorb all thetension variation but there is a limit for the absorption of the tensionvariation. Further, as the loom is turned at high speed, the influencescaused by such a delay from the time of tension variation becomesstronger so that the pile warp tension is sharply increased or reduced,resulting in large tension variation. Such a large and sharp tensionvariation can not be completely absorbed, arising a problem that loomstoppage frequently occurs owing to missing plush loop and mispickingcaused by deflective shedding. In conclusion, according to the techniqueof Sulzer, the loom has to be operated at a low revolution speed,resulting in the deterioration of productivity.

[0004] Meanwhile, the technique for positively driving a tension rollerfor pile warp (hereinafter referred to as pile warp tension roller)generally comprises a support means for displaceably supporting the pilewarp tension roller, an electromotive actuator for biasing the tensionroller in a direction to apply tension via the supporting means, and apile warp tension controller for controlling the pile warp tension at avalue lower than a value at the time of steady operation insynchronization with the relative motion between a reed and a wovencloth to move toward or away from each other for pile formation.

[0005] As a means for setting the pile warp tension at a value lower avalue at the time of steady operation, there are following twotechniques. One technique is disclosed in Japanese Patent No. 2,622,685wherein a tension roller is stopped (position holding state) from abiasing state in synchronization with the relative motion between a reedand a woven cloth to move toward each other for pile formation, or thetension roller is moved by a given amount in the direction to reduce thepile warp tension in synchronization with the relative motion betweenthe reed and the woven cloth to move away from each other. The othertechnique is disclosed in Japanese Patent Laid-Open Publication No.2001-131845 wherein a biasing force from the electromotive actuator isset at a value lower than a value at the time of steady operation insynchronization with the relative motion between a reed and a wovencloth to move toward or away from each other for pile formation.

[0006] Although the foregoing two techniques are improved somewhatcompared with the technique of Sulzer, these techniques are not completebecause inertia of the tension roller and that of the supporting membersthereof act when the biasing force relative to the tension roller iscontrolled, there occurs the delay of the motion (delay of displacement)or excessive motion of the tension roller, resulting in the pile warptension variation. Furthermore, when the loom is turned at highrevolution speed, such a delay of the motion or excessive motion becomeslarge which appears as the sharp increasing or reducing of the pile warptension as it is, because the tension roller is formed of a rigid body,arising problems that quality of a textile is deteriorated owing tomissing plush loop or, mispicking is induced by defective shedding ofthe pile warp so as to stop the loom.

SUMMARY OF THE INVENTION

[0007] Accordingly, it is an object of the invention to provide a pileloom provided with a pile warp tension controller capable of setting apile warp tension at an appropriate value even at a high speed operationof the pile loom.

[0008] To achieve the above object, a first aspect of the invention is apile warp tension controller for controlling a tension roller associatedwith a relative motion between a reed and a woven cloth which iseffected in accordance with a pile formation, and it is structured suchthat the tension roller which is driven as set forth above is deformablein the range of winding of a pile warp. The pile warp tension controllerof the invention is structured such that an electromotive actuator istorque driven in response to a torque command value which is set incorrespondence with an applied tension or the electromotive actuatorselectively undergoes torque control mode or positional control mode.Further, a position command value is set at the pile warp tensioncontroller for executing positional control during a period when arelative motion between the reed and the woven cloth for pile weavingand a torque command value corresponding to the applied tension is setduring a period other than the period when the relative motion isperformed. Since the pile warp tension controller is varied in pile warptension at the time of switchover between the relative motion, at thetime of driving of the electromotive actuator with a control modecorresponding to respective commands, namely, owing to the drivingmanner of the tension roller, more in detail, owing to the factor suchas the relative motion between the reed and the woven cloth or warpshedding motion which is performed for pile weaving, either the drivingfor reducing such variation or the driving for rendering the pile warptension at a value suitable for the pile formation is included. In thelatter driving, as a more preferable example, at a period when therelative motion is performed and at least at a prescribed period toinclude a beating time within a period when the relative motion isperformed for pile formation, the electromotive actuator is controlledfor applying tension at a period other than the predetermined period.

[0009] “The relative motion between the reed and the woven cloth” forpile formation includes an operation for preparing a reed escape amount(appropriate distance between the position of the cloth fell caused bythe movement of a cloth and the original position of the cloth fell,i.e. beating position of the cloth fell) by moving the reed and thewoven cloth away from each other and an operation for forming a pile bymoving the reed and the woven cloth toward each other. The pileformation process concretely includes both cloth movable type pile loom(pile loom for displacing a cloth fell position of the woven cloth backand forth while beating position is fixed), a reed moving type(sword-beater type) pile loom (pile loom for displacing the beatingposition back and forth while the cloth fell of the woven cloth isfixed).

[0010] As set forth in the prior art, in the weaving process, although abiasing force relative to the tension roller is generally controlled forpile formation, there occurs the increase or reduction of the pile warptension owing to inertia of supporting members of tension roller orinertia of tension roller per se, resulting in the delay of the motionof the tension roller or excessive motion of the same.

[0011] On the other hand, according to the invention, since the tensionroller has been already in an elastic deformed state while undergoing abiasing force and the tension roller per se is elastically deformedwhile undergoing the pile warp tension variation so as to change warppath length, it is possible to control a sharp warp tension variation.Accordingly, even if the loom is turned at high speed, a drawback whichis caused by the tension variation and has not been solved so far by theconventional technique, namely, a drawback that the rate of operation isdeteriorated owing to mispick caused by missing plush loop or thedefective shedding of the pile warp can be solved, and hence it ispossible to manufacture a high quality pile fabric with efficiency. Thearrangement for driving the tension roller for reducing the pile warptension variation caused by the relative motion between the reed and thewoven cloth is not limited to the structure set forth above, and it maybe structured such that the electromotive actuator is electrically,synchronously driven associated with the relative motion between thereed and the woven cloth for pile weaving or it may be mechanicallydriven via a driving mechanism coupled with the main shaft of the loomor swingably driving the supporting means associated with the relativemotion between the reed and the woven cloth which is effected incorrespondence with the pile weaving. The swingable driving of thetension roller means that the tension roller is displaceably driven backand forth relative to the warp in a direction to cancel the increase andreduction of the warp tension caused by the relative motion between thereed and the woven cloth. For example, even if there occurs an electricdelay of the driving of the tension roller or a mechanical swingabledriving amount is roughly set at a value which is deviated somewhat froman ideal value and there occurs the pile warp tension variation owing tothe relative motion set forth hereinbefore, the tension roller which hasbeen in an elastic deformed state while undergoing a biasing forthundergoes such tension variation in the same manner as set forth above,so that the tension roller is elastically deformed by it self to changethe warp path length, thereby restraining a sharp warp tensionvariation.

BRIEF DESCRIPTION OF DRAWINGS

[0012]FIG. 1 is a side view showing a main portion of a pile loom;

[0013]FIG. 2 is an enlarged sectional view of a tension roller;

[0014]FIG. 3 is an enlarged sectional view of another tension roller;

[0015]FIG. 4 is a block diagram of a pile warp tension controller;

[0016]FIG. 5 is a block diagram of another pile warp tension controller;

[0017]FIG. 6 is a view showing a step of forming piles and an example ofcontrol thereof;

[0018]FIG. 7 is a timing chart showing an operation during one repeatcycle;

[0019]FIG. 8 is a block diagram of still another pile warp tensioncontroller; and

[0020]FIG. 9 is a side view showing a main portion of another pile loom.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0021] FIGS. 1 to 4 show an example where a tension roller is driven byan electromotive actuator, and the electromotive actuator is biased witha torque which is lower than a torque at the time of steady operation asto set a pile warp tension at a desired low value during a period ofrelative motion between a reed and a woven cloth, at least a givenperiod including a beating time for forming piles, the tension roller isextended in a direction of weaving width, and the tension roller isformed by a spring member which is curved and formed in correspondencewith a pile warp path.

[0022] First of all, FIG. 1 shows an entire cloth movable type pile loom1 (hereinafter referred as simply as pile loom) as an example. The pileloom 1 causes relative motion between a reed 28 and a woven cloth 7 bymoving a cloth fell 7 a of the woven cloth 7 back and forth periodicallyfor pile formation by a pile warp 2.

[0023] Many pile warps 2 are wound around an outer periphery of alet-off beam 3 in a sheet shape in a weaving direction, and it ispositively let off by the revolution of a let-off motor 4, then it iswound around outer peripheries of a guide roll 5 and a tension roller 6,and thereafter supplied to a direction of the cloth fell 7 a. The guideroll 5 is turnably supported at a fixed position relative to a loomframe 10.

[0024] The tension roller 6 is turnably supported back and forth by atension lever 8 and a fulcrum shaft 9 serving as a mechanical supportingsystem relative to the loom frame 10. The tension roller 6 is structuredsuch that it is elastically deformed when receiving a pile warp tensionin the range of winding of the pile warp 2, described later, and issupported not to turn relative to the tension lever 8. The tension lever8 is turnably supported by the fulcrum shaft 9 at a fixed position ofthe loom frame 10. The tension lever 8 may be biased by a spring, notshown, in a direction to always apply a constant tension relative to thepile warp 2, if need be.

[0025] The fulcrum shaft 9 is driven by an electromotive actuator 15such as an AC servomotor or a torque motor via gears 13 a, 13 b. Theelectromotive actuator 15 is controlled by a pile warp tensioncontroller 40, and is turned in either direction to generate a turningforce (torque) as a given force proportional to a current value.

[0026] In such a manner, the pile warp tension controller 40 converts anelectric signal serving as an output of the pile warp tension controller40 into a turning force which is proportional to the magnitude of theelectric signal by controlling the electromotive actuator 15, andfurther converts the turning force into displacement (movement) of thegears 13 a, 13 b, the fulcrum shaft 9, the tension lever 8 and thetension roller 6, thereby causing the displacement to act upon the pilewarp 2. As a result, a tension of the pile warp 2 can be adjusted by theoutput of the pile warp tension controller 40 in a weaving process.

[0027] Meanwhile, the let-off motor 4 is controlled by a let-offcontroller 16. The let-off controller 16 indirectly measures amount ofconsumption of the pile warps 2 as weaving operation advances bysampling the displacement of the tension roller 6 or tension lever 8which is detected by a displacement detector 17 at a prescribed period,and drives the let-off motor 4 in a let-off direction in correspondencewith the thus measured amount of consumption, and lets off the pile warp2.

[0028] The let-off controller 16 adds number of revolutionscorresponding to the displacement of the tension roller 6 to a basicnumber of revolutions (revolution speed) of the let-off motor 4 orsubtracts number of revolutions corresponding to the displacement of thetension roller 6 from the basic number of revolutions of the let-offmotor 4, and drives the let-off motor 4 by the total number ofrevolutions so as to always let off the pile warp 2 during weavingoperation. Since the let-off controller 16 is a feed back control systemand normally responds by a large time constant, and hence it does notcontrol a temporal displacement of the tension roller 6 back and forthat the time of shedding motion or at the time of pile formation.

[0029] Meanwhile, a ground warp 18 is supplied by a ground warp let-offbeam 19 as in the past, and it is wound around a back roll 20, andguided forward to insert into heddles 21, and forms a shedding 22together with the pile warp 2 by the vertical movement of the heddles21. The ground warp 18 crosses with a weft 23 at the position of theshedding 22 and forms the woven cloth 7 of a pile textile together withthe weft 23 which is beaten by the reed 28. The woven cloth 7 is woundaround an outer periphery of a take-up beam 27 after passing through atake-up roll 25 which is displaceable back and forth, a take-up roll 26at a fixed position, and a plurality of guide rolls 25 a, 25 b.

[0030] Owing to the movable type pile loom 1, the back roll 20 is alsodisplaceably supported back and forth by a ground warp tension lever 29which is freely turnable relative to a fulcrum shaft 30 in the samemanner as the take-up roll 25, and it is biased by a tension spring 31in a direction to apply a given tension to the ground warp 18. Further,the fulcrum shaft 30 is supported by a fulcrum shaft 30 b so as to swingby a supporting arm 30 a back and forth relative to the loom frame 10.

[0031] The take-up roll 25 is swingably supported by a lever 25 c and alever shaft 25 d back and forth, and is coupled with the supporting arm30 a by a link 25 e, and it is moved back and forth by a terry motionmechanism 24 such as a terry cam which is driven by a main shaft 41 ofthe pile loom 1. In such a manner, both the back roll 20 and the take-uproll 25 swing back and forth associated with the pile formation cycle,and cause the woven cloth 7 and cloth fell 7 a to move back and forth.

[0032] Although a beating position is always constant in the portabletype pile loom 1, both the woven cloth 7 and the cloth fell 7 a aremoved back and forth. Both the take-up roll 25 relative to the wovencloth 7 and the back roll 20 relative to the ground warp 18 aresupported in a state to be displaceable back and forth as set forthabove, and when they move back and forth after a first pick beating in astate where they are synchronous with the turning of the main shaft 41by the terry motion mechanism 24, the cloth fell 7 a is caused to moveforward (cloth take up side) and an appropriate reed escape amount isgiven by two times of loose picking. In the meantime, “first pick” meansbeating the weft 23 until the weft 23 reaches the cloth fell 7 a while“loose picking” means beating until the weft 23 reaches merely up to aposition corresponding to the reed escape amount in front of the clothfell 7 a but not to beat completely the weft 23 to reach the cloth fell7 a.

[0033] The pile warp 2 is let off while the let-off amount is increasedor decreased in response to the movement of the tension roller 6 duringthe let off operation at a basic speed without direct relation with theback and forth motion of the back roll 20 and the take-up roll 25. Onthe other hand, although the turning of the ground warp let-off beam 19,the take-up roll 26 and the take-up beam 27 is performed by the drivingof the electric motor or a mechanical let-off mechanism or a windingmechanism, the arrangements thereof are the same as the prior technique,and hence the explanation thereof is omitted.

[0034] When the pile loom 1 operates to progress the weaving, the pilewarp 2 is woven in the woven cloth 7, and hence the weaving sequentiallyadvances forward so that the tension of the pile warp 2 graduallyincreases. Since the tension roller 6 moves forwards associatedtherewith, the tension lever 8 is turned clockwise in FIG. 1. Thedisplacement of tension roller 6 or the tension lever 8 at this time isalways detected by the displacement detector 17 as an electric signalwhich is proportional to the displacement amount. Although the detectionis always continuously performed, the detected electric signal isutilized for the let-off control every prescribed sampling cycle by asampling technique, described later.

[0035] Since the signal detected by the displacement detector 17 becomesan input of the let-off controller 16, the let-off controller 16 samplesthe detected signal at a prescribed timing and finds an average value ata prescribed units of picking and also calculates the command speedbased on a deviation amount relative to a standard value, so that whenthe let-off motor 4 is positively turned, the let-off beam 3 of the pilewarp 2 is turned in the let-off direction so as to let off the pile warp2 to restrain the increase of the tension of the pile warp 2, therebycancelling a sharp tension variation of the pile warp 2 caused by thedisplacement of the tension roller 6 or the tension lever 8.

[0036] The let-off motion of the ground warp 18 is let off by theelectric motor type let-off mechanism or mechanical let-off mechanism.Provided that the ground warp 18 is performed by the electric motor typelet-off mechanism, the controller thereof always continuously lets offthe ground warp 18 in response to the command speed corresponding to abasic speed, detects the tension of the ground warp 18 during a let-offprocess, compares the detected tension with a target tension, correctsthe basic speed so that the tension of the ground warp 18 is equal tothe target tension value, and finally outputs the corrected results asthe command speed. Thus the let-off motion of the ground warp 18 isalways continuously performed, and the let-off motion speed is varied inresponse to the deviation relative to a target tension value.

[0037]FIGS. 2 and 3 largely show the main portion of elasticallydeformable tension roller 6. First of all, the tension roller 6 shown inFIG. 2 is structured such that a sheet metal cylindrical spring member 6b is eccentrically fixed to a bar 6 a which extends in a weaving widthdirection so as to envelope from the outside by a bolt 6 c and a holder6 d. The pile warp 2 is wound around a deformed circumferential surfaceof the cylindrical spring member 6 b and undergoes the increase of thetension so as to render the spring member 6 b flat. Since the springmember 6 b is rendered elastically deformed in flat, the tension of thepile warp 2 is reduced at the time of sharp variation. The material,thickness, curvature (radius) of the cylindrical spring member 6 bserving as a typical constituent of the tension roller 6 are determinedconsidering the tension value or the variation range of the pile warp 2.

[0038] The tension roller 6 shown in FIG. 3 is structured such that oneend of a sheet metal C-shaped prismatic spring member 6 b iseccentrically fixed to chamfered surface of a bar 6 a which extends in aweaving width direction so as to envelope from the outside by a bolt 6 cand a holder 6 d. The pile warp 2 is wound around an elasticallydeformable portion of the C-shaped prismatic spring member 6 b andundergoes the increase of the tension so that a free end of the springmember 6 b is deformed. The tension of the pile warp 2 is reduced by theelastic deformation of the spring member 6 b at the time of a sharpvariation. The material, thickness, curvature (radius) of the springmember 6 b serving as a typical constituent of the tension roller 6 aredetermined considering the tension value or the variation range of thepile warp 2.

[0039]FIG. 4 shows an example of an internal construction of the pilewarp tension controller 40. In this example, the pile warp tensioncontroller 40 displaces the tension roller 6 into the tensionapplication direction relative to the pile warp 2 in accordance with thetarget torque while setting the target torques which is changed forevery period within one repeat period for forming a pile and driving thefulcrum shaft 9 of the tension lever 8 by the electromotive actuator 15with the target torque for every plural periods within one repeat periodat the weaving time.

[0040] A driving control portion 42 shown in FIG. 4 receives plural,e.g., two commands of target torques T1, T2 from a tension settingportion 43 and drives the electromotive actuator 15 in a prescribedturning direction. The target torques T1, T2 correspond to a targettension value which is applied to the pile warp 2 during a specificperiod within one repeat and they are given by a setting device 44. Aselection signal generator 45 receives a setting content given by asetting device 47 and a turning angle θ of a main shaft 41 from an angledetector 46 which is coupled to the main shaft 41, and outputs aselection signal for torque switching to the tension setting portion 43at a prescribed timing in synchronization with a pile formation.

[0041]FIG. 5 shows control examples (1), (2), (3) relative to back andforth movements of the woven cloth 7 and the cloth fell 7 a within onerepeat period (three picks), the position of the tension roller 6, andturning intervals R1, R2, R3. In FIG. 5, the control example [1]corresponds to the completion of the pile formation and the statedepicted by (2), (3), (4) correspond to a loose picking and a statedepicted by (5), (6) correspond to a first pick, and the pile formationis completed during these states.

[0042]FIG. 7 shows the relation between the turning angle θ of the mainshaft 41 within one repeat period (three picks) shown on a lateral axisand a beating timing, weft timing, shedding of the ground warp, sheddingof a pile warp, movement of a woven cloth, a selection signal, and atarget torque shown on a vertical axis.

[0043] The driving control portion 42 shown in FIG. 4 sets the targettorque T2 within the turning intervals R1, R3 which are determined toinclude the relative motion between the woven cloth 7 and the reed 28based on the control example [1], namely, corresponding to the lowtension value of the pile warp 2 in a shedding state of the pile warp 2,and also sets the target torque T1 corresponding to a normal tensionvalue of the pile warp 2 at the turning interval R2. It is needless tosay that the target torque T2 is smaller than the target torque T1.

[0044] In the first pick depicted by (5), (6), there does not occurmissing plush loop by such a setting of the tension so that a pileformation is ensured. It is needless to say that the low tension valueof the pile warp 2 can be appropriately changed considering the sheddingstate of the pile warp 2 and the moving condition of the woven cloth 7.Further, the selection period of the target torques T1, T2 is notlimited to those as illustrated, which can be changed, if need be. It isneedless to say that plural torques can be set even in the turninginterval R2, if need be, and these torques may be switched overtherebetween.

[0045] With the pile loom 1 having such a construction, the pile warptension is preferably set at a high value to stabilize the operation ofthe pile loom 1 to prevent the mispicking caused by the inferior warpshedding at the turning interval R2 so as to perform the pile formationat a desired height and maintains at a low tension suitable for the pileformation at the turning intervals R3, R1 so as to perform the pileformation at a desired height. Accordingly, the pile warp tensioncontroller 40 changes the torque which biases the tension roller 6 forevery period of the pile formation cycle, and the tension roller 6 isstructured to be displaced such that the applied torque balances withthe pile warp tension.

[0046] However, inertia of the tension roller 6 acts on the tensionroller 6 so that there occurs a delayed movement or excessive motion ofthe movement of the tension roller 6. If the tension roller 6 is formedof a rigid body as made conventionally, the tension variation becomesprominent associated with such a delayed or excessive motion of themovement of the tension roller 6 so that the missing plush loop ormispicking occurs as described in the prior art. Whereupon, according tothe pile loom of the invention, the tension roller 6 is structured suchthat it is elastically deformed while undergoing warp tension shown inFIGS. 2 and 3 and it has been already deformed somewhat by the biased orapplied torque. Accordingly, when the tension roller 6 undergoes tensionvariation, it is elastically deformed by itself so that the warp pathlength is changed, resulting in the slackness of a sharp tensionvariation. This is described more in detail next.

[0047] Before the beating for a pile formation, the relative motionbetween the reed 28 and woven cloth 7 to move toward each other iseffected for effecting the pile formation, wherein (1) when the tensionroller 6 is delayed relative to the relative motion between the reed 28and woven cloth 7, the pile is hardly formed because the tension of thepile warp 2 increases and there occurs missing plush loop. At this time,the tension is prone to increase instantly but the tension roller 6undergoes the increase of the tension and is deformed so that the pathlength of the pile warp 2 is shortened to restrain the increase of thetension. The tension lever 8 undergoes the increase of reaction forcefrom the tension roller 6 and moves in a direction to restrain theincrease of the tension, and also undergoes the decrease of reactionforce by the movement thereof so that the tension roller 6 returns thedeformation to the original state. Accordingly, the tension of the pilewarp 2 during the period of relative motion between the reed and wovencloth is maintained at a desired low value so as to reduce the sharpincrease of tension which has occurred so fat so that a pile is formedin accordance with the reed escape amount at the beating time caused bythe relative motion between the reed 28 and the woven cloth woven cloth7.

[0048] On the other hand, (2) when the tension roller 6 is renderedexcessive relative to the relative motion between the reed 28 and thewoven cloth woven cloth 7, the tension of the pile warp 2 lowersopposite to the previous case (1), so that it stops owing to themispicking caused by the defective shedding of the pile warp 2. Althoughthe tension of the pile warp 2 lowers instantaneously but the tensionroller 6 which is in the tension applied state has been alreadydeformed, and hence it undergoes the reduction of tension to recover tooriginal state so that the warp path length is deformed so as to extend,thereby restraining the reduction of tension. The support member such asthe tension lever 8 undergoes the decrease of reaction force from thetension roller 6 and moves in a direction to restrain the reduction oftension, then undergoes the increase of reaction force by the movementthereof so that the tension roller 6 returns the deformation to theoriginal state. Accordingly, the pile warp tension is maintained at thedesired low value during the period of relative motion between the reed28 and woven cloth 7 so that the sharp reduction of tension which hasoccurred so far is reduced, ensuring the picking which is performed inparallel with the relative motion.

[0049] After the beating for the pile formation, the relative motionbetween the woven cloth 7 and reed 28 is performed so as to move awayfrom each other in order to prepare the reed escape amount for the pileformation, wherein (3) when the tension roller 6 is delayed relative tothe relative motion between the woven cloth 7 and the reed 28, the pilewarp tension increases to pull out the pile warp 2 from the alreadyformed pile so that the pile height is reduced, resulting in theoccurrence of missing plush loop. In the same operation as the case (1),the increase of the pile warp tension is reduced to prevent the pilewarp 2 from being pulled out so that the occurrence of missing plushloop can be prevented. (4) When the tension roller 6 operates earlierthan the relative motion between the woven cloth 7 and the reed 28, thetension reduces so that the weft 23 is caught by the pile warp 2 whichis in defective shedding so that mispicking occurs and the pile loom 1stops. As a result, in the same operation as the case (2), reduction ofthe pile warp tension is reduced. Since the pile warp tension is notreduced from the desired low tension during the period of time ofrelative motion between the woven cloth 7 and the reed 28, the pickingwhich is performed in parallel with the relative motion is ensured.

[0050] Even if there occurs delayed or excessive motion of the tensionroller 6 before or after the beating for the pile formation,instantaneous increase of reduction of tension is reduced to maintain adesired low tension so that a desired pile is formed and a drawback thatthe operation of the pile loom 1 is damaged by the mispicking is solved.As a result, a weaving can be performed even at a high revolution of thepile loom 1 which has not been realized so far, thereby improving aproductivity and quality of the woven cloth 7.

[0051]FIG. 6 shows an example of an internal construction of anotherpile warp tension controller 40. In this example, the pile warp tensioncontroller 40 has a speed command portion 48 and a stop command portion49 in addition to a tension setting portion 43, wherein the outputs ofthese constituents are selectively switched over therebetween by aswitching portion 50 to output the switched output to a driving controlportion 42. A selection signal generator 45 receives a setting contentgiven by a setting device 47 and a turning angle θ of a main shaft 41and outputs a selection signal to the switching portion 50 so as toswitch over the switching portion 50 at a prescribed timing insynchronization with the pile formation.

[0052] During weaving, the pile warp tension controller 40 drives aelectromotive actuator 15 while a torque control step, a speed controlstep, and a stop control step are switched over therebetween inaccordance with a period of time to include the relative motion betweena woven cloth 7 and a reed 28 within one repeat period of time for thepile formation so that a force acting act upon a tension roller 6, amoving speed of the tension roller 6 and a stopping position of thetension roller 6 are controlled.

[0053] The torque control is executed in response to a command value ofa torque T which is an output of the tension setting portion 43 so as tobias the tension roller 6 with a prescribed torque in a tensionapplication direction at the time of sharp tension variation of the pilewarp 2. The speed control is executed in response to a command of speedV which is an output of the speed command portion 48 by forciblemovement in the direction to reduce the tension of the pile warp 2.Further, a stop position control is executed in response to a command ofspeed B from the stop command portion 49 so as to maintain the tensionroller 6 in a stop state at a prescribed position. The command of thespeed B includes zero speed for stop operation.

[0054] The selection signal generator 45 executes the control example[2] upon receipt of the turning angle θ of the main shaft 41 from theangle detector 46 and outputs either the selection signal from thetorque control, speed control, the stop control to the switching portion50 at a prescribed timing during the pile formation. A timing forswitching over between the torque control, the stop control, the speedcontrol is set by the setting device 47. Accordingly,, the switchingportion 50 selects a control mode in response to the turning angle θ ofthe main shaft 41 and selectively outputs the command value of torque T,a command of speed V and a command of speed B to the driving controlportion 42. The driving control portion 42 controls the driving of theelectromotive actuator 15 with a control mode corresponding torespective commands.

[0055] According to the control example [2] shown in FIG. 5, theelectromotive actuator 15 undergoes speed control by speed V1 which isoutputted corresponding to the amount of movement during almost periodof a turning interval R1 at the time of forward movement of the wovencloth 7, namely, when the reed 28 and cloth fell 7 a are moved away fromeach other, so that the tension roller 6 is displaced while maintainingthe pile warp tension at the original low tension T2, subsequently, theelectromotive actuator 15 undergoes stop control in response to thecommand of speed B at the end period of the turning interval R1 so as toimmediately stop the tension roller 6 so as to eliminate the movementcaused by inertia of the tension roller 6. Thereafter, the torquecontrol is executed in response to the command value of the torque Tduring a turning interval R2 upon completion of the forward movement ofthe woven cloth 7 so as to maintain the tension of the pile warp 2 at atarget torque T1 which is set higher than the low tension T2.Thereafter, the stop control is executed in response to the command ofthe speed B to immediately stop the tension roller 6 during the periodof turning interval R3 so as to eliminate the movement caused by inertiaof the tension roller 6, thereby rendering the tension of the pile warp2 at the tension T2 to fit for the pile formation which is lower thanthe target torque T1 by reducing the pile warp tension whileinterlocking with the relative motion between the reed 28 and the wovencloth 7 to move toward each other while the stop state is maintained.Thereafter, the pile warp 2 is beaten toward the cloth fell 7 a wherethe first picked weft 23 is moved backward, thereby forming a freshpile. Then, the step is returned to the initial step where the wovencloth 7 performs the forward movement so that the electromotive actuator15 undergoes speed control in response to the speed V1 which isoutputted corresponding to the amount of movement or momentum, and hencethe pile warp tension is maintained at the original low tension T2 as itis. That is, since the warp tension fitted for pile formation ismaintained even after the beating for pile formation, the pile warp 2can be pulled out from the newly formed pile, so that there does notoccur a drawback that the pile height lowers. Since the tension roller 6is driven so that the pile warp tension is varied corresponding to thepile formation cycle in the same manner as the control example [1] shownin FIG. 5, and the tension roller 6 is structured to be elasticallydeformable, inertia of the tension roller 6 or inertia of the supportingmember such as the tension lever 8 for supporting the tension roller 6acts on the driving of the tension roller 6 during a front or rearperiod of beating for pile formation, resulting in the occurrence ofdelayed or excessive motion of the tension roller 6. As a result, evenif a sharp tension variation occurs, the tension roller 6 undergoes sucha tension variation and it is elastically deformed so as to change thewarp path length so that the tension variation is reduced.

[0056] According to the control example [3] shown in FIG. 5, theelectromotive actuator 15 undergoes the stop control in response to thecommand of the speed B during the turning interval R1, and undergoestorque control in response to the command value of the torque T duringthe turning interval R2 so as to maintain the tension of the pile warp 2at the target value, thereafter undergoes the stop control in responseto the command of the speed B during the turning interval R3 so as toeliminate inertia caused by the movement of the tension roller 6 so thatthe tension roller 6 is immediately stopped and the tension of the pilewarp 2 is maintained at a low value by the set value.

[0057] The control examples [1] to [3] are formed to set the pile warptension at values fitted for pile formation and they are preferable forpile formation. However, according to a pile fabric which is relativelyeasily woven, various command values can be set so as to always applythe same applied tension to the pile warp 2 without limiting to abeating period for pile formation and also without limiting to suchcontrol examples. Further, it is possible to simplify the constructionso as to position and drive the tension roller 6 relative to themovement of the woven cloth 7. The driving means of the tension roller 6is exemplified hereinafter.

[0058] The first concrete example is an example to electrically andsynchronously driving an electromotive actuator 15 in correspondencewith the relative motion between the reed 28 and the woven cloth 7. FIG.8 shows an example of an internal construction of a pile warp tensioncontroller 40 corresponding to the electrical and synchronous driving ofthe electromotive actuator 15. This example is similar to the deviceshown in FIG. 4 but the former is different from the latter in respectof the arrangement of a speed command portion 56 instead of the tensionsetting portion 43 shown in FIG. 4.

[0059] The pile warp tension controller 40 includes a speed commandportion 56 in addition to a reference voltage supply 54 for setting theamount of movement l1 for moving the tension roller 6 in correspondencewith the amount of relative motion between a reed 28 and a woven cloth7, and outputs an output of the speed command portion 56 to a drivingcontrol portion 42. A selection signal generator 45 switches over acommand speed at a timing corresponding to the setting of the relativemotion between the reed 28 and the woven cloth 7 to move toward or awayfrom each other upon reception of a setting content which is given by asetting device 47 and a turning angle θ of a main shaft 41, and outputsa selection signal to the speed command portion 56. More in detail, aperiod when the woven cloth 7 is moved forwards and a period when thewoven cloth 7 is moved backwards are set in the setting device 47 asrespective timings. The selection signal generator 45 recognizes a firstpick period or loose picking period based on the turning angle θ, andoutputs the selection signal which corresponds to respective set periodsto the speed command portion 56. Meanwhile, the amount of movement l1for moving the tension roller 6 is inputted to the speed command portion56 via the reference voltage supply 54 and the speed command portion 56can output a positional command value corresponding to the amount ofmovement l1 and the moving direction as a speed command value. The speedcommand portion 56 outputs a speed command value V1 (V1>0) during theturning interval R1 where the woven cloth 7 is moved forwards, forexample, as illustrated in the control example [4] shown in FIG. 5, anddisplaces the tension roller 6 in conformity with the movement of thewoven cloth 7 while it outputs a speed command value V3 (V3<0) duringthe turning interval R3 where the woven cloth 7 is moved backwards todisplace the tension roller 6 backwards, and it outputs a speed commandvalue V2 (V2=0) during the turning interval R2 where the woven cloth 7is not moved, to stop the tension roller 6. In such a manner, thetension variation associated by the movement of the woven cloth 7 can bemore reduced compared with the device in which a conventional tensionroller is passively driven by moving and displacing the tension roller 6in conformity with the amount of movement of the woven cloth 7.

[0060] Although the electromotive actuator 15 is driven insynchronization with the turning of the main shaft 41 in the foregoingexamples, the tension roller 6 can be driven by a swing motion mechanismhaving a driving source of the main shaft 41, namely, by a drivingmechanism. FIG. 9 shows an entire pile loom 1 provided with such adriving mechanism which is different from the pile loom 1 in FIG. 1 inrespect of the provision of a driving mechanism 60 in place of drivingmechanisms 13 a, 13 b, serving as members for driving a fulcrum shaft 9,an electromotive actuator 15 and a pile warp tension controller 40. Thedriving mechanism 60 is a mechanism for converting a turning movementfrom the main shaft 41 into a swing motion corresponding to the movementof the woven cloth 7 which is in turn acts on a fulcrum shaft 9 so as toproduce motion like the terry motion mechanism 24. The pile loom 1 canbe more simplified by omitting the driving mechanism 60 and the movementof a terry motion mechanism 24 is transmitted to the fulcrum shaft 9 viasome type of mechanical means to drive the fulcrum shaft 9.

[0061] Even if there occurs the pile warp tension variation by theoccurrence of electric delay caused by the driving of the tension roller6 or by setting roughly the amount of mechanical swingable driving whichis somewhat deviated from an ideal value, or by the relative motionbetween a reed 28 and the woven cloth 7, the tension roller 6 isprovided to be elastically deformable as shown in FIG. 2 or FIG. 3 sothat the tension roller 6 which is in an elastically deformable stateupon reception of a biased force in the same manner as the previousembodiment, and it undergoes tension variation and is elasticallydeformed by itself so that the warp path length is changed, therebyrestraining the warp tension variation.

[0062] The invention is not limited to the cloth moving type pile loom 1but can be applied to a sword-beater type (reed moving type) pile loom1.

[0063] According to the first aspect of the invention, the pile warptension controller 40 controls the driving of the electromotive actuatorduring a period when the relative motion between the reed and the wovencloth is performed and the tension roller is structured to beelastically deformable in the winding range of the pile warp.

[0064] Accordingly, the tension roller is driven in a tension swingingdirection during a period before beating for pile formation which isimportant to the pile formation and during a period after beating forpile formation, and hence even if there occurs a delayed or excessivemotion of the tension roller with respect to the relative motion betweenthe reed and the woven cloth, resulting in the occurrence of a sharppile warp tension variation, the tension roller which is in anelastically deformable state upon reception of the biased forceundergoes such a tension variation and is elastically deformable so asto change the warp pass length, thereby reducing the tension variation.Accordingly, a desired low tension state is maintained so that the pilehaving a given pile height can be formed reliably and inconvenience ofdamaging the operation of the pile loom caused by mispicking can besolved. It is possible to perform weaving even at high speed ofrevolution which has not been realized so far, thereby improvingproductivity and quality of the woven cloth.

[0065] According to the second aspect of the invention, a torque commandvalue corresponding to an applied tension is set for every period andthe electromotive actuator can be torque driven while selecting anappropriate command value so that the tension control of the pile warpcan be ideally performed.

[0066] According to the third aspect of the invention, since the pilewarp tension controller is structured to select either the torquecontrol mode or positional control mode so that an appropriate controlmode is performed reliably by selecting either control mode, ensuringthe pile formation.

[0067] According to the forth and fifth aspects of the invention, theelectromotive actuator is driven at a tension which is suitable for pileformation at a value lower than the normal pile warp tension during aperiod including a period before or after the beating for pile formationwhich is a period important for the pile formation, the pile formationis more ensured.

[0068] According to the sixth and seventh aspects of the invention, thearrangement for driving the tension roller is more simplified, and evenif there occurs a delayed or excessive motion of the tension roller or amechanical swingable driving amount is roughly set at a value which isdeviated somewhat from an ideal value and there occurs the pile warptension variation owing to the relative motion set forth hereinbefore,the tension roller undergoes such a tension variation and is elasticallydeformed by itself to change the warp pass length, thereby restrainingsharp warp tension variation.

[0069] According to the eighth aspect of the invention, since thetension roller is structured by a leaf spring member which extends in adirection of width of weaving and is curved in correspondence with thewarp path, the warp tension variation in the direction of width ofweaving is prevented by the elastic deformation of the leaf springmember, thereby correcting a locally minute tension variation.

What is claimed is:
 1. A pile loom comprising an electromotive actuatorfor driving a tension roller relative to a pile warp and a pile warptension controller for controlling the driving of the electromotiveactuator in correspondence with pile weaving, wherein the tension rolleris elastically deformable in the range of winding of the pile warp. 2.The pile loom according to claim 1, wherein the pile warp tensioncontroller torque drives the electromotive actuator in response to atorque command value which is set in correspondence with an appliedtension.
 3. The pile loom according to claim 1, wherein the pile warptension is structured such that the electromotive actuator undergoesselectively either a torque control or a positional control, a positioncommand value for executing the positional control during a period whena relative motion between a reed and a woven cloth is performed for pileweaving and a torque command value corresponding to the applied tensionfor executing the torque control during a period other than the periodwhen the relative motion is performed are respectively set in the pilewarp tension controller, and wherein the pile warp tension controllerselects the corresponding command values or controls to drive theelectromotive actuator when periods of the relative motion between thereed and woven cloth are switched therebetween.
 4. The pile loomaccording to claim 2, wherein the command value for applying a tension,which is lower than a tension applied during a second period other thana first period, is set in the pile warp tension controller during thefirst period which is determined to include at least a beating time forforming a pile within a period when the relative motion between the reedand woven cloth is performed for pile weaving, and wherein the pile warptension controller selects the corresponding torque command value totorque drive the electromotive actuator when periods of relative motionbetween the reed and woven cloth are switched therebetween.
 5. The pileloom according to claim 3, wherein the positional command value duringthe first period which is determined to include at least the beatingtime for forming a pile within a period when the relative motion betweenthe reed and woven cloth for pile weaving is performed is set in thepile warp tension controller at a value to reduce the applied tensionduring the second period owing to the cooperation with the relativemotion between the reed and woven cloth.
 6. The pile loom according toclaim 1, wherein a positional command value for reducing the tensionvariation of the pile warp caused by the relative motion between thereed and woven cloth for pile weaving is set in the pile warp tensioncontroller, and the pile warp tension controller performs a positionalcontrol of the electromotive actuator in response to the positionalcommand value.
 7. A pile loom comprising support means, for displaceablysupporting a tension roller relative to a pile warp, and drivingmechanisms connected to a main shaft of the pile loom for swingablydriving the support means, in correspondence with the relative motionbetween the reed and the woven cloth which is performed incorrespondence with a pile weaving, wherein the tension roller iselastically deformed in the range of winding of the pile warp.
 8. Thepile loom according to any of claims 1 to 7, wherein the tension rolleris formed of a leaf spring which is extended in a weaving widthdirection and curved in correspondence with a warp path.